Nucleo-cytoplasmic interactions affecting biological performance of in .

Hybrids have been successfully used to improve crop productivity, including Brassicas. Nucleo-cytoplasmic interactions have been reported to influence the expression of resistance to insect pests in several crops. We studied the effects of Cytoplasmic Male Sterility (CMS) in carrying alien cytoplasms and their respective maintainer (B) lines on the antibiosis mechanism of resistance, involving development, survival, reproduction potential and population build-up of mustard aphid, , and the levels of defense phyto-chemicals. Present findings revealed that the numbers of aphids/plant, aphid multiplication rate and aphid resistance index were lower on CMS under natural, CMS under artificial infestation conditions, and under both the test conditions indicating nucleo-cytoplasmic interactions for aphid reaction. Across cytoplasms, nymphal, reproductive and total developmental periods were significantly longer on SEJ 8, NPJ 161, LES 39, and NPJ 93, while the reproductive potential and survival were lower on PM 30, Pusa Tarak and SEJ 8 as compared to other nuclear backgrounds. Across nuclear backgrounds, nymphal, reproductive and total developmental periods were significantly longer on CMS, while reproductive potential and survival were lower on and CMS as compared to other cytoplasms. Total glucosinolates were significantly greater and myrosinase lower in Pusa Agrani, SEJ 8, LES 39, PM 30, NPJ 112, and Pusa Tarak as compared to the other nuclear backgrounds. Furthermore, total glucosinolates were significantly greater and myrosinase lower in CMS and as compared to other cytoplasms. The studies suggest that CMS as well as cytoplasmic and nuclear gene interactions regulate the expression of defense compounds such as glucosinolates and determine the expression of resistance/susceptibility to . These findings shall help in identification of suitable tolerant nucleo-cytoplasmic combinations for their deployment in hybrid breeding program.